The present invention is generally related to ultrasound systems, and, more particularly, the present invention is related to optical interconnect and method for optically coupling an ultrasonic probe and an imaging console using a quantum-well device.
Ultrasound systems typically comprise a hand-held probe having an array of ultrasound transducer elements which transmit during a transmit mode of operation a vibratory signal to be propagated into a medium and receive during a receive mode of operation a reflected signal from within the medium. By controlling the time delay and the applied voltages of an array of such transducers, the focal point of an ultrasound beam can be controlled and scanned. A transducer array can be used both as a transmitter and receiver. It thus forms an image by properly controlling the beam-forming parameters.
In known ultrasound array imaging systems, each transducer element is commonly connected by an individual miniaturized coaxial cable to a single analog channel followed by an analog-to-digital converter and delay circuit. Thus, for example, a 128-channel system may use up to 128 delay circuits plus all other associated electronic components. At typical imaging frequencies of 1-20 MHz, delay circuits need timing accuracy in the order of a few nanoseconds. The transducer array may be assembled separately from the console electronics unit which provides the electrical control, signal processing, and power conditioning. The interconnect between the transducer unit and the electronic unit becomes complicated as the number of array elements increases. For example, the large number of individual coaxial cables collectively becomes difficult to maneuver. The degree of complexity increases even more as the sensor array becomes two dimensional (2D) for three dimensional (3D) or volumetric scanning. Sometimes additional components, such as multiplexers, may be installed in the probe to attempt to reduce the cable count. Unfortunately, the additional components may increase the cost of the imaging system and may impact the overall reliability of the system.
Previous attempts to use optical fibers to communicate ultrasound information are believed to have been generally based on one of the following two techniques. In the first known technique, the received echo signal is used to drive an optical source. Unfortunately, such optical sources typically have relatively low efficiency and hence they result in high power consumption devices. For example, the amount of power dissipated in a probe handle may be prohibitive since it may result in exceeding heat dissipation constraints. In the second known technique, the power dissipation in the handle is reduced by putting the optical source in the console, and then modulating the signal from that optical source with information from the acoustic echo. Unfortunately, this technique is also believed to have failed to provide a practical solution since such technique also results in relatively high power consumption, very low dynamic range, or both. For example, a standard Mach-Zehnder modulator may dissipate in the order of one watt.
In view of the foregoing issues, it would be desirable to provide systems and techniques that could reduce the complexity of the interconnects and cabling in ultrasound probes, such as multirow or two-dimensional (2D) ultrasound transducer arrays. It would be further desirable to provide a greatly improved optical modulator that has a relatively high dynamic range and that further allows for relatively low power dissipation in the operation of the imaging system so as to handle operation of a large number of channels using an optical fiber interconnect.